OBJECTIVES: Asthma is a complex, heterogeneous disease that can be subdivided into numerous overlapping phenotypes or segments on the basis of clinical, patho-physiological, and inflammatory markers. Novel treatments including biologics have targeted immunologic phenotypes within moderate-severe asthma. Lack of consistency in definitions of severity and control status among studies reporting the prevalence of various segments presents challenges. We reviewed publications reporting prevalence of asthma segments based on the definitions of control and severity using Global INitiative for Asthma guidelines (GINA) to understand the prevalence of the heterogeneous segments of asthma and to identify gaps. METHODS:  A systematic review was conducted in PubMed and Embase to identify publications reporting prevalence of severe (GINA step 4 and 5) or moderate (GINA step 3) asthma populations and GINA asthma control (i.e. controlled, partially controlled or uncontrolled). Search was limited to studies in the English, between 1999 and 2016, and assessing adults and/or adolescents. RESULTS: Of 405 titles and abstracts screened, nine studies were included in the analysis with eight studies from Europe, one from Nigeria, and none from the Americas. Majority of patients (66%-84%) with uncontrolled asthma were severe across Europe and Nigeria. In a study in Germany in allergic asthma, 13% were severe (19% of whom were uncontrolled) and 29% were moderate (4% uncontrolled). In Italy, 43% of Asthma-COPD Overlap Syndrome (ACOS) had uncontrolled asthma. In Spain, the prevalence of severe, uncontrolled asthma was 4% of all asthmatics. CONCLUSIONS:  Moderate-severe uncontrolled asthma represent the highest clinical and economic burden and unmet needs. Literature reporting prevalence of asthma segments is sparse with inconsistent definitions and a denominators. Robust real-world data analyses are needed to determine and define phenotypes and respective overlaps empirically to aid in mapping opportunities, unmet needs, designing trials, establishing care pathways, and defining payer and pricing policies.